The term “flexible cable,” as used herein, means any flexible, elongated, energy or fluid-conducting device, such as a cable composed of one or more electrical wires or optical fibers, a fluid-conducting hose for conducting compressed air or a hydraulic fluid used as a medium for transmission of motive power, a flexible conduit used to convey a gas, a liquid, or another fluid material for use in a machine or industrial process, a flexible actuator such as a Bowden wire, or a flexible rotating shaft with or without a non-rotating sheath. Such flexible cables are used, for example, to connect relatively moving parts of a machine such as a machine tool, an industrial robot, or a conveyor or other material-handling or material-carrying machine, such as a hoist or other machine used in a civil engineering application.
When a flexible cable is connected to a moving part, torsion, flexion, and tensile forces applied to the cable as a result of movement of the moving part can result in damage to, or distortion of, the cable. Cable guides have been used to avoid such damage and distortion.
As shown in FIG. 10, a typical cable guide 100 is composed of a number of links, each comprising a pair of side plates 102 disposed on both sides of a cable C and connecting plates 101 connecting the side plates. The connecting plates 101 are provided both above and below the cable, and together with the side plates 102, form an elongated channel through which the cable extends. The side plates 102 on each side of the guide are hinged to one another so that the guide can bend at least in a single plane. Usually, the flexion of the guide is limited to a specific minimum radius of curvature in order to avoid kinking of the cable C.
Typically, the cable guide has a fixed end 105 and a moving end 106. Where a cable guide of sufficient length is folded on itself by a bend 120 as shown in FIG. 8, it is possible for two portions of the guide to come into face-to-face contact with each other. Friction between the contacting parts of the guide can obstruct smooth reciprocating motion. Moreover, frictional contact over time can cause wear and eventual breakage of the cable guide. Breakage can also result from interference between projecting portions of the two facing parts of the guide.
On Jul. 8, 2005, one of the inventors of the invention filed a Japanese patent application, 2005-200236, describing a skate for interposition between the facing parts of a folded cable guide. An example of the skate disclosed in the Japanese patent application is depicted in FIGS. 8, 9(a) and 9(b). This skate 400 is composed of a series of interconnected units that can be sandwiched between facing parts of a bent cable guide 100, as shown in FIG. 8, to prevent the parts of the cable guide from coming into direct contact with each other.
As shown in FIGS. 9(a) and 9(b), the skate 400 is composed of a series of interconnected skate units in aligned, sequential relationship. Each skate unit comprises a pair of parallel rails 430, and each rail has a pair of rollers 420 which extend laterally outward. The rollers are rotatable on pins fixed to the rails, and the diameters of the cylindrical parts of the rollers are greater than the height of the rails. The rollers are also provided with flanges at their outer ends, which keep the skate units aligned with the cable guide. The parallel rails 430 of each skate unit are maintained at a predetermined spacing by U-shaped connecting blocks 450, which also serve to connect the skate units to one another. To this end, connecting pins 440 extend, laterally with respect to the longitudinal direction of the skate, through the side walls of the blocks 450, and through holes formed in the rails 430, and are secured by Cotter pins 460 or by other suitable devices. The connecting pins allow the skate units to articulate freely relative to the connecting blocks and relative to one another at least about the axes of the connecting pins. The articulation of the skate units allows a full length skate to be used even when both of the facing parts of the cable guide bend during use.
The skate 400 can be built to any desired length by interconnection of an appropriate number of skate units. However, the assembled skate unit can be difficult to carry, especially if it is composed of a large number of skate units. Moreover, since the skate units are connected to the connecting blocks 450 by pins 440, which are secured by additional devices such as Cotter pins 460, it is difficult to assemble the skate by connecting the skate units to the connecting blocks, and also difficult to disassemble the skate unit by disconnecting the skate units from the connecting blocks.
This invention enables the skate units to be connected and disconnected more easily, so that the skate can be more readily assembled, and so that the skate can be easily disassembled for transport from one place to another.